/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *	  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.sirona.counters;

import org.apache.sirona.Role;

import java.io.Serializable;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * A <code>Metric</code> is a numerical indicator of some monitored application state with support for simple
 * statistics.
 *
 *
 */
public interface Counter {
	Key getKey();

	void reset();

	void add(double delta);

	void add(double delta, Unit unit);

	AtomicInteger currentConcurrency();

	void updateConcurrency(int concurrency);

	int getMaxConcurrency();

	// --- Statistical indicators --------------------------------------------

	double getMax();

	double getMin();

	long getHits();

	double getSum();

	double getStandardDeviation();

	double getVariance();

	double getMean();

	double getSecondMoment(); // here for aggregation etc but not (yet?) a human metric so not in MetricData

	public static class Key implements Serializable {
		private final String name;
		private final Role role;
		private int hash = Integer.MIN_VALUE;

		public Key(final Role role, final String name) {
			this.role = role;
			this.name = name;
		}

		@Override
		public String toString() {
			return "name=" + name;
		}

		@Override
		public boolean equals(Object o) {
			if (this == o) return true;
			if (o == null || getClass() != o.getClass()) return false;

			final Key key = (Key) o;
			return name.equals(key.name) && role.equals(key.role);

		}

		@Override
		public int hashCode() {
			if (hash == Integer.MIN_VALUE) {
				hash = name.hashCode();
				hash = 31 * hash + role.hashCode();
			}
			return hash;
		}

		public String getName() {
			return name;
		}

		public Role getRole() {
			return role;
		}
	}
}
